fix-calendars-without-_classrooms.js

/**
 * MongoDB script that attempts to remove bastards calendars
 * A calendar is a bastard calendar when:
 *  - has an ObjectId _classroom property
 *  - Classroom Object with that _classroom ObjectId() no longer exists.
 */

var calendars = db.calendars.find({ _classroom: { $ne: null }})
  , i = 0
  , l = calendars.count()
  , bastardsEventsDontMatter = false;

print("\nProcessing " + l + " calendars with _classroom fields.\n");

calendars.forEach(function (calendar) {
  i++;
  //printjson(calendar);
  var classroom = db.classrooms.findOne({ _id: calendar._classroom });
  if (!classroom) {
    print(i + " -\t'" + calendar.name + "' calendar is a fucking bastard !");

    var calevents = db.calevents.find({ _calendar: calendar._id })
      , countEvents = calevents.count();

    if (countEvents) {
      print('\tbut has ' + countEvents + ' events.');

      if (bastardsEventsDontMatter) {
        print('\tanyway ... removing calendar');
        db.calendars.remove({ _id: calendar._id });
      }
      else {
        print('\tNot removed. Disassociating the Calendar with the inexistent Classroom');
        db.calendars.update({ _id: calendar._id }, { $set: { _classroom: null } });
      }
    }
    else {
      print('\tremoving calendar');
      db.calendars.remove({ _id: calendar._id });
    }

  }
  checkError();
});

function checkError () {
  var err = db.getLastError();
  if (err) {
    print('Error updating calendar: ' + err);
    print('Updated ' + i + ' calendars before failure');
    exit(1);
  }
}